Chapter 5
GNATHOSTOMES FISHES (1)
Chondrichthyes
Two major innovations make this group successful:
jaws
developed from the first gill arch
paired appendages (fins)
These two characteristics allowed them to become predaceous jaws
allowed them to catch and consume prey
paired appendages gave
fishes more maneuverability - fins add stability and control
there
is no good indication for the origin of appendages - one simply the
fin-fold theory
Gnathostomes developed into a number of clades:
Ancestral gnathostomes =>
Placoderms -
extinct
Chondrichthyes
Acanthodians - extinct
Osteichthyes
Flourished in the late Silurian and Devonian
Placodermi - armoured fishes An extinct group well-represented
in the fossil record
Name means “plate skin”
because skin had dermal bone plates
much like Ostracoderms;
however, placoderms had jaws and paired appendages
no evidence
of vertebral column
had a notochord but no vertebral column
varied in size- some as large as 6m in length
well-represented
in the Devonian Period - some were benthic while others appeared to
be more predaceous
Class CHONDRICHTHYES - CARTILAGENOUS FISHES
skeleton composed of calcified cartilage
bone is thought
to be more primitive to cartilage
500-700 species; almost all
marine
have jaws and paired appendages
have 5-7 external
gill openings or gill slits and one reduced gill called a spiracle or
false gill
no swim bladder
internal fertilization
may
be viviparous, oviparous, or ovoviviparous
Two Parental Clades for Chondrichthyes
Subclass Elasmobranchii
the sharks, rays,
and skates
~700 species
several gill openings
placoid
type of scales
Elasmobranchii subdivided into two groups:
pleurotremata (“side
hole”) - refers to location of gills on the side of the head:
sharks
hypsotremata (“below hole”) - refers to
location of gills on the ventral surface: rays and skates
gills
of both groups ventilated by a double pump and by the spiracles
in
some sharks ventilation requires a continuous movement for water to
pass over the gills
sharks lack a swim bladder; have an oil
(squalene) produced by the liver which acts as a density control
device by adjusting overall body density
PRIMARY REPRODUCTIVE PATTERNS
Oviparous - egg layers
Ovoviviparous - live birth
during development the young
are nourished by the yolk
when the egg is fertilized, it has a
large yolk and the embryo develops in the uterus while obtaining
nutrient from the stored yolk
Viviparous - live birth
young
receive nourishment from some type of placental attachment
nourishment comes from the mother’s blood, secretions, or
other tissues
Generalized Classification of Elasmobranchii:
Order Squalimorphes (Squaloids) - spring and green
dogfish sharks, basking and megamouth sharks
~80 species
live
in cold deep waters
Squalus
acanthius - dogfish shark
Order Galeomorphs (Galeoids) - contains most of
the sharks
~250 species
all with five gill openings
dominant carnivores of shallow waters
hammerhead, great
white, whale shark
Order Batoidea (Rajiformes)- skates and rays
~425
species
skates have pointed nose and lay eggs, rays give live
birth
Family: Echinorhinidae - Bramble sharks Order:
Squalimorphes (bramble, sleeper and dogfish sharks) Subclass:
Elasmobranchii - sharks and rays
Large (3-4 m), wide-ranging,
deepwater sharks in cold-temperate to tropical seas.
Circumglobal
distribution on continental and insular shelves and slopes from 11 to
900 m, on or near the bottom.
Short-nosed, cylindrical sharks
with no anal fin
Skin covered with coarse denticles or enlarged
thorns
Feed on a variety of benthic and neritic fishes,
including other sharks as well as crabs, octopuses and squids
Thought to suck in their prey by suddenly expanding their
mouths and pharynxes when in range
Ovoviviparous and lack a
yolk sac placenta
Family: Squalidae - Dogfish sharks Order: Squalimorphes (bramble,
sleeper and dogfish sharks) Subclass: Elasmobranchii (sharks and
rays)
Atlantic, Indian and Pacific Oceans
No lateral
teeth or barbels. Dorsal fin with or without spines
5 gill
openings anterior to pectoral fin
Maximum length at 6.3 m,
reported for Somniosus microcephalus
This family includes the
smallest sharks in the world.
Family: Ginglymostomatidae - Nurse sharks
SubOrder: Orectolobiformes (carpet sharks) Order Squalimorphes
Subclass: Elasmobranchii (sharks and rays)
Marine, all oceans.
Small to large sharks with nasoral grooves, short to long barbels,
small spiracles behind eyes.
Two spineless fins and an anal fin
A short precaudal tail
Common, small to
large, nocturnal, inshore bottom sharks with a circumglobal
distribution in subtropical and tropical waters, in depths from the
intertidal down to at least 70 m.
Cruise and clamber on the
bottom with their mouths and barbels close to the substrate while
searching for food.
They use their short, small mouths and
large mouth cavities as a bellows to suck in their prey: bony fish,
crabs, shrimps, lobsters, squids, octopuses, corals, sea urchins, sea
squirts.
Family: Cetorhinidae - Basking sharks Order:
Squalimorphes Subclass: Elasmobranchii (sharks and rays)
Marine,
all oceans, highly migratory.
Gill openings exceptionally
large; gill rakers elongate, plankton feeders, teeth reduced.
The
tail is nearly symmetrical with keel on caudal peduncle.
Fifth
gill opening in front of pectoral fin.
The family contains the
world's second largest fish, reportedly reaching 40 feet (12 m) in
TL.
Family: Sphyrnidae - Hammerhead, Bonnethead, and
Scoophead sharks SubOrder: Carchariniformes (ground sharks) Order
Galeomorphes Subclass: Elasmobranchii (sharks and rays)
Marine,
coastal; occasionally in brackish water.
Global (chiefly warm
waters).
Head laterally expanded, with eyes and nasal openings
much widely set than in other sharks.
No spiracle.
A
maximum length of 4.5 m was reported for Sphyrna tudes.
Feed on
a wide variety of bony fish, elasmobranchs, cephalopods, crustaceans,
and other prey.
Family: Lamnidae - Mackerel sharks, White sharks
SubOrder: Lamniformes (mackerel sharks) Order Galeomorphes Subclass:
Elasmobranchii (sharks and rays)
Distribution: global. Large
sharks with pointed snouts and spindle-shaped bodies.
Large
gill openings.
First dorsal fin large, high, erect and angular
or somewhat rounded; second dorsal and anal fins minute.
Caudal
peduncle with a distinct keel; large teeth; fifth gill opening in
front of pectoral fin; spiracle sometimes absent.
Maximum
length up to 6.4 m or more.
Fast swimming predators - some are
man-eaters.
Ovoviviparous without a yolk-sac placenta but with
uterine cannibalism.
Family: Pristidae - Sawfishes SubOrder:
Pristiformes (sawfishes) Order Galeomorphes Subclass: Elasmobranchii
(sharks and rays)
Atlantic, Indian, and Pacific Oceans.
Snout
elongated into a long flat blade with teeth of uniform size deeply
embedded on each side.
No barbels. Head depressed with the body
more or less resembling a shark.
Two distinct dorsal fins.
Giant fishes of coastal waters, entering estuaries and
ascending large rivers for great distances. Used for food and
regarded as exciting game fishes because of their size. Although
generally harmless to humans, their large size and sawlike beak make
them dangerous when hooked or speared.
Of the many nominal
species only four appear to be valid.
Family: Rajidae - Skates Order: Rajiformes (skates and rays)
Subclass: Elasmobranchii (sharks and rays)
Benthic rays
occurring in all oceans, from Arctic to Antarctic waters and from
shallow coastal shelves to abyssal regions; some species enter
brackish waters.
Disc quadrangular to rhomboidal.
Mouth
transversed to arched, with numerous teeth.
Five pairs of
ventral gill slits.
Tail very slender, with lateral folds,
usually 2 reduced dorsal fins and a reduced caudal fin.
Electric
organs weak, developed from caudal muscles.
Skin prickly in
most species, the prickles often in a row along midline of dorsal.
Oviparous; eggs in a horny capsule with four long tips.
Skates
feed on other benthic organisms. Skate wings are considered good
eating.
Family: Anacanthobatidae - Smooth skates Order:
Rajiformes (skates and rays) Subclass: Elasmobranchii (sharks and
rays)
Known from South Africa, Natal, and the tropical western
Atlantic; also from Taiwan.
A terminal filament of varying
length arising from a small, bluntly rounded protuberance at the tip
of the snout.
Dorsal fins absent, but membranous caudal fin
present. Five pairs of small, ventral gill slits.
Dorsal and
ventral surfaces of disc smooth, without dermal denticles.
Tail
slender, a bit shorter than disc. Small skates of slope regions in
tropical/subtropical waters.
Family: Platyrhinidae - Thornbacks Order:
Rajiformes (skates and rays) Subclass: Elasmobranchii (sharks and
rays)
Atlantic, Indian and Pacific Oceans.
Body form
intermediate between that of a shark and a skate.
Tail stout,
not well demarcated from body.
Dorsal fins 2; distinct.
Caudal
fin present.
Denticles arranged in a row on dorsal midline.
No
spine in tail.
Family: Rhinobatidae - Guitarfishes Order:
Rajiformes (skates and rays) Subclass: Elasmobranchii (sharks and
rays)
Atlantic, Indian and Pacific Oceans mostly in tropical
coastal waters.
Body form intermediate between that of a shark
and a skate.
Also called shovelnose sharks.
Numerous
small, blunt teeth in jaws.
Two large dorsal fins; caudal fin
well developed.
Denticles arranged in a row on dorsal midline.
No spine in tail.
They reach moderate to large size and
are important commercial species in many coastal nations.
Ovoviviparous.
Feed on bottom organisms, including
mollusks and crustaceans, but will also take small fishes.
Family: Dasyatidae - Sting rays SubOrder:
Myliobatiformes (eagle rays, stingrays and mantas) Order: Rajiformes
Subclass: Elasmobranchii (sharks and rays)
Chiefly marine; also
in brackish and freshwater - Atlantic, Indian and Pacific Oceans.
Side of head continuous with anterior margin of pectoral fin.
Dorsal fin totally absent or indistinct, when present.
Disc
about 1.2 times as broad as long.
No caudal fin.
Tail
long and whip-like.
Most species with at least 1 long venomous
spine on tail, which can cause excruciating pain to humans.
Largest
species to about 4m length or width.
Live-bearing
(ovoviviparous).
Family: Mobulidae - Manta rays and devil rays
SubOrder: Myliobatiformes (eagle rays, stingrays and mantas) Order:
Rajiformes Subclass: Elasmobranchii (sharks and rays)
Atlantic,
Indian and Pacific Oceans.
Head differentiated from disc.
Eyes
and spiracles on sides of head.
Mouth ventral in Mobula and
terminal in Manta.
Size of gill openings almost the length of
eye. Length of tail much greater than disc. Some with spines.
Dorsal
fin small. Caudal fin lacking. Three functional paired limbs. The
cephalic pair of fins aid in feeding and are said to be essentially
the anterior subdivision of the pectorals.
Some reach about 6.1
m and weigh over 1360 kg.
Subclass Holocephali
chimaeras
or ratfish
~25 species
gills covered by an operculum
no
placoid scales
Chimaeridae - Chimaeras or ratfishes Order:
Chimaeriformes
Subclass: Holocephali
Atlantic, Pacific, and Indian oceans in
temperate to tropical waters, mostly below 200 m
Short and
rounded snout
First dorsal fin erectile, with a strong spine;
second dorsal fin long and low
Diphycercal tail - vertebral
column runs straight to the tip, dividing the caudal fin
symmetrically
Anal fin confluent with caudal fin in Hydrolagus
; separate in Chimaera
Feed on small fishes and bottom
invertebrates
Males with head clasper
Oviparous; large
tadpole-shaped egg capsules are deposited on substrate
Dorsal
spine with associated poison gland, the venom of which hurts humans
Family: Rhinochimaeridae - Longnose chimaeras Remark: Found at scattered localities worldwide in temperate and tropical seas, in 200 to more than 2,000 m depth. Long and pointed snout, lacking a hooklike process. First dorsal fin erectile, with a strong, mildly toxic spine; second dorsal fin long, low and not falcate. Diphycercal tail, i.e., the vertebral column is extending to the tip and divides the caudal fin symmetrically; caudal fin may be confluent with or separate from anal fin. Oviparous: egg-cases spindle-shaped, with broad filamentous horizontal flanges
CONFIGURING USER STATE MANAGEMENT FEATURES 73 CHAPTER 7 IMPLEMENTING
INTERPOLATION 41 CHAPTER 5 INTERPOLATION THIS CHAPTER SUMMARIZES POLYNOMIAL
PREPARING FOR PRODUCTION DEPLOYMENT 219 CHAPTER 4 DESIGNING A
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